The present invention relates to a capsule for preparing coffee in a beverage production machine. It also relates to a coffee capsule system including such capsule.
Single-serve beverage capsules are very popular because they provide a fresh tasting beverage quickly, conveniently and in a clean fashion. Therefore, certain beverage capsule systems propose to extract a coffee liquid from roast and ground coffee ingredients contained in a capsule that opens under pressure when a sufficient amount of water fills the capsule. More particularly, the pressure of liquid increases in the capsule before the delivery face of the capsule opens thereby conferring a good quality of extraction.
In particular, the NESPRESSO® capsule system, as described in EP0512470B1, is based on the principle that an extraction face of the capsule is torn against relief and recessed elements of a capsule holder in the beverage production machine. The extraction face tears at the location of these relief elements and/or recessed elements on reaching the breaking stress to enable the liquid, e.g., coffee extract, to be removed after extraction of the coffee under a certain positive pressure. EP0512468B1 also describes a capsule which is adapted for such extraction process and device.
Although such process produces an outstanding coffee quality due to this retarded opening of the extraction face of the capsule, the opening of the face may be difficult to repeatedly control as it depends on many different factors. Therefore, the extraction face is generally formed of a membrane having a very precisely controlled thickness of aluminum, in particular, of about 30 microns. Despite all care taken for designing such capsule, the opening of the membrane may be more or less retarded and the consistency of the flow may also be affected in some way depending on the characteristics of the ground coffee, the sizes of the perforations through the membrane, etc.
Many patents describe capsules which do not fit into a beverage production device comprising a capsule holder comprising relief and recessed elements as described in EP0512470B1.
EP1273528B1 relates to a closed supple capsule designed to be extracted under pressure comprising a first foil that allows water to pass at atmospheric pressure by piercing with a piercing means and a second foil that is such that it only allows water to pass when an excess pressure between 0.1 and 3 bar is attained during extraction; the foil being made of filter paper or of non-woven with a sufficiently close meshwork. However, such capsule is configured for insertion in a coffee machine comprising a large opening at the delivery side of the capsule such as described in EP0242556. The delivery foil of such capsule would perforate at the beginning of extraction against a capsule holder of a coffee machine as described in EP0512470B1.
U.S. Pat. No. 3,292,527 relates to an apparatus and cartridge wherein the cartridge comprises a truncated cup sealed by an upper foil, the bottom of the cup being a disc formed of small perforations in the fashion of a sieve. This disc is intended more particularly for infusions, lixivations and decoctions (coffee, tea, lime-blossom, etc.). The apparatus has a capsule holder with a large hole such that a direct flow can be provided from the capsule with reduced contact with the machine.
WO02/058522A2 relates to a cartridge and method for making fluid comestibles comprising a bulb-like or cup-like body which comprises one or more compartment for beverage ingredients, a filter and possibly a wall formed of a small orifice to provide a restriction to the beverage flow enabling the production of foam or coffee cream. However, the capsule is not designed for matching a capsule holder comprising relief and recessed elements.
EP1579792B1 relates to an integrated cartridge for extracting a beverage from a particulate substance comprising an internal volume comprising valve means, in particular, a pad or disc of a resilient material which comprises at least one through slit or orifice that is normally closed for insulating the internal volume of the cartridge and for retaining liquid residuals inside the internal volume when the beverage extraction has been terminated. However, such cartridge is relatively complicated in its conception and cannot by associated to a capsule holder comprising relief and recessed elements.
Accordingly, there is a need for improved products of these types and this need is now met by the products and methods of the present invention.